It may be obvious to you when the "code" changes but yesterday the music stopped and I found a prompt to ok downloading a new release. No hint on a version and I don't see a way to find out the current version.

Can you send me this file ? I can't seem to access it at all. I'd like to fix the Shared Object part at the least. Actually these paths look fine, other than the extra "///" part. The empty .sol files wil get written to later, and the v1_PerfComp.sol should already exist.

Ok, the problem is that movie_def_impl takes bitmap_character_def by raw pointer but then puts it into a vector of intrusive_ptr.
Now, if the vector grows due to a resize the intrusive_ptr refcount is temporarly decremented resulting in a destruction if going down to zero.

This is because the caller doesn't store the newly created instance in an intrusive_ptr from the start.

That happens when the tag loader (maybe the bitmap decoder in this case) doesn't make sure it doesn't attempt to read past the end of tag. We should use ensureBytes or similar instead, which IIRC would throw an exception interrupting the parser.

A conseguent thing to do is avoid to completely interrupt
parsing but only drop parsing of a single tag, or even not
throw the exception at all in this case and try to work
with the data we understand.

Finally, the decoder itself might be completely bogus..
(this is known to be true for some sound decoding)

The collapsed dimension is likely more a malformed SWF then a real ERROR (and could also not even be considered a malformation).
listswf shows for it:
Frame size: (0,0)x(0,0)
Seems intentional...
I'm not sure if gnash still executes code in it though (which is likely what that movie is needed for). Should be easy to check using makeswf -s0x0 ...

As for the tuner I could not reproduce the segfault.
Can you reproduce it consistently ? Offline ? Which configuration of Gnash ?

Just a note: both movies are likely output by OpenLaszlo (looking at the names of variables/characters).